Theme aware plugin (#4499)

* Migrate theme manager to infrastructure and added it as input to public API instance

* Working event-delegate for PublicAPIInstance

* Theme aware UWP applications

* Theme aware program plugin

* Update query icon on theme change

* Theme aware calculator plugin

* Fix issue with query running before theme change

* Theme based changes in ImageLoader

* Removed ErrorIcon direct references and added references from ImageLoader

* Nit fixes

* Removed unnecessary TODO in UWP.cs

* Added preference to theme based icons

* Added IDisposable interfaces to unsubscribe events

src/modules/launcher/Wox.Plugin/IPublicAPI.cs

@@ -57,6 +57,16 @@ namespace Wox.Plugin
         [Obsolete]
         void ShowApp();
 
+        /// <summary>
+        /// Get current theme
+        /// </summary>
+        Theme GetCurrentTheme();
+
+        /// <summary>
+        /// Theme change event
+        /// </summary>
+        event ThemeChangedHandler ThemeChanged;
+
         /// <summary>
         /// Save all Wox settings
         /// </summary>